Typically, a leisure vehicle, for example, a motorcycle is equipped with a rider's seat which is open to the outside. Thus, a rider may freely mount the rider's seat. A key switch is positioned in an exposed region near the rider's seat, for example, an instrument panel located in front of the rider's seat. For this reason, the motorcycle is more likely to be stolen in contrast to automobiles, which are equipped with a rider's seat into which a third party is unable to enter.
Under the circumstances, Japanese Patent No. 3112585 discloses a theft prevention apparatus in which an engine is able to start-up only when a key that matches a key switch is inserted into the key switch to turn on a main switch and a communication device that is equipped in a vehicle and is configured to store a predetermined user identification (ID) code matches a user ID code received from a portable device (card) carried by a rider.
In this theft prevention apparatus, the communication device equipped in the vehicle is required to be always held to await the user ID code from the portable device. In a case where the user goes outside for a long time period, for example, for a trip, and the vehicle is left unsteered for the long time period, battery power of the vehicle is wasted. This is problematic because battery capacity of a motorcycle is smaller than that of a four-wheeled vehicle.
The rider's seat of the motorcycle is open to the outside as described above, and the rider in many cases steers the motorcycle, wearing gloves while driving. To start the vehicle, the rider takes the gloves off to take the key out of a pocket, inserts the key into the key switch, and turns the key to a predetermined position. Thereafter, the rider puts back on the gloves. Such a procedure may be burdensome to the rider.
To address these circumstances, a key system (or keyless system) of a vehicle has been proposed, in which a knob of a main switch that replaces the key and the key switch is turned on, and when a rider carrying a portable device in a pocket or the like comes closer than a predetermined distance away from the vehicle the user ID code is communicated between the portable device and the communication device equipped in the vehicle to detect whether or not there is a match, and the engine is able to start-up if the match is detected.
However, in the keyless system of the motorcycle equipped with the seat which is open to the outside, if the rider (owner) carrying the communication device comes closer than the predetermined distance away from the vehicle, or otherwise the rider is checking the motorcycle from the side with someone other than the rider (owner) mounting the seat, then the user ID of the portable device code matches the user ID code of the communication device, so that someone may start-up the engine. As a result, theft of the vehicle may occur.
Furthermore, the above mentioned problems arise in leisure vehicles other than motorcycles.